A network consists of network devices linked together and managed by a network operator. The network devices exchange data in the form of packets transmitted over links. Two networks may meet at a network edge, and the network operators for the two networks may have an agreement to allow exchange of data at the network edge. A network device in a first network may address packets to a network device in another network, requiring the packets to be transmitted across a network edge. When these packets travel through multiple networks, there may be alternative routing options. The network devices determine which route will be used in accordance with one or more networking protocols.